Which side of the VisiSens sensor foils has to face the sample?

All sensor foils have a removable color tag (O2 = blue, pH = red, CO2 = green) on their insensitive side which has to face the detector unit, while the untagged (sensitive) side has to face the sample.

If our are integrating the sensor foil into a vessel, the side with the tag has to be glued to the vessel wall. If you are covering a sample with the foil, the untagged side has to face the sample surface.